Plant cells synthesize a variety of defense compounds upon stimulation with pathogen-derived or plant cell wall-derived molecules termed elicitors. While much is known concerning the nature of these elicitors and the types of defense molecules produced in response to elicitation, virtually nothing is known about the sequence of events involved in transducing the extracellular elicitor signal into the cell's nucleus. The objective of this research is to identify those signal transduction and amplification processes which occur at the plasma membrane during elicitation. Using signal transduction pathways in animal cells as models, the goals of this project are to evaluate the possible participation of the following signaling mechanisms during elicitation of phytoalexin formation: 1) calcium transport, 2) proton transport, 3) changes in membrane potential, 4) changes in trans-plasma membrane dehydrogenase activity, and 5) changes in phosphatidylinositol turnover. Emphasis will be placed on mechanisms 1, 2, and 3. A detailed understanding of signal transduction processes in plant cells is of great intrinsic interest and may eventually contribute to the rational design of strategies for manipulating the various defense and growth responses in plants.
